1. Field of the Invention
The present invention relates to an IC testing device and more particularly, to a probe card for wafer level testing.
2. Description of the Related Art
Wafer testers are applied to test wafer yield, employ probes to contact die pads of a tested wafer, and send out testing signals to perform a functional test of the wafer to screen out defective wafers.
With reference to FIG. 10, a conventional probe card of a wafer tester has a wiring board 50, a holding member 51, an interposer 52, a space transformer 53, a probe head 54 and two leaf springs 55. The holding member 51 is mounted on a bottom of the wiring board 50 and has an opening 510 facing downwardly. The interposer 52 is stacked on a top of the space transformer 53, and the interposer 52 and the space transformer 53 are mounted inside the holding member 51. The wiring board 50, the interposer 52 and the space transformer 53 respectively have connection terminals formed thereon coming into electrical connection with one another. The probe head 54 is mounted in the opening 510 of the holding member 51 by abutting against the leaf springs 55. The probe head 54 has a plurality of probes formed thereon to bring into electrical contact with the connection terminals of the space transformer 53. The holding member 51 and the leaf springs 55 are fastened on the wiring board 50 by multiple bolts 56.
When the wafer tester is operated, the probes on the probe head 54 contact a wafer to be tested. The wafer tester transmits test signals to the tested wafer through a microprocessor, and the test signals are transmitted to the tested wafer through the wiring board 50, the interposer 52, the space transformer 53 and the probe head 54. Responding signals generated by the probe head 54 are sent back to the microprocessor for the microprocessor to perform a function analysis. A wafer test can thus be conducted.
When any one of the interposer 52, the space transformer 53 and the probe head is damaged and needs to be replaced, as the holding member 51 and the leaf springs 55 are fastened on the wiring board 50 by the bolts 56, the bolts 56 must be unscrewed first. Then, the holding member 51, the interposer 52, the space transformer 53, the probe head 54 and the leaf springs 55 can be disassembled, and the damaged component can be replaced by a functioning counterpart. However, since the holding member 51, the interposer 52, the space transformer 53, the probe head 54 and the leaf springs 55 are already detached, there is no way to tell which component is damaged. In order to do the troubleshooting, an operation personnel must test all the components one by one, replace the damaged component and reassemble all the components on the wiring board 50. Hence, a single faulty component can cause a lot of inconvenience in maintenance.
Moreover, when the space transformer 53 is mounted on the interposer 52, the connection terminals between the interposer 52 and the space transformer 53 need to be calibrated to ensure that the electrical connections among connection terminals of the interposer 52, the space transformer 53 and the probe head 54 function as intended. Additionally, when the probe head 54 is mounted on the space transformer 53, the electrical connection among the connection terminals of the probe head 54 and the space transformer 53 needs to be calibrated once again. The calibration procedures are complicated and tedious and also cause operational inconvenience.